* Stock index up 49.73 points, or 0.39 pct, at 12,849.64 * Energy stocks lead the way * Mining, consumer issues also strong By Cameron French TORONTO, March 15 (Reuters) - Canada's main stock index was modestly higher on Friday as rising commodity prices pushed up energy and mining shares while consumer stocks were helped by strong U.S. data. The index's heavily weighted energy subgroup, which was the main boost to the Canadian market on Thursday, continued to play the role